late 13c., prouesse, from Old French proece "prowess, courage, brave deed" (Modern French prouesse), from prou, later variant of prud "brave, valiant," from Vulgar Latin *prodem (source also of Spanish proeza, Italian prodezza; see proud). Prow was in Middle English as a noun meaning "advantage, profit," also as a related adjective ("valiant, brave"), but it has become obsolete. "In 15-17th c. often a monosyllable" [OED].